1. Field of the Invention
This invention relates to a tamper resistant closure for use on a container and, in particular, to a tamper resistant closure containing a tear strip in combination with a tamper evident band containing a flange that is hinged to said band.
2. Description of the Prior Art
For safety and security reasons, tamper resistant closures are known. One such previous closure is described in European Patent Application Number 90310078.2 published on Apr. 10th, 1991. The closure in that Application has a tamper evident band having a movable flange thereon with the band being connected to the closure along a weakened line. The weakened line can be formed by scoring or by circumferentially-spaced bridges. When the closure is installed on the container, the flange and tamper evident band override a ring on the container. When the closure is desired to be removed, sufficient force must be exerted on the closure to sever the tamper evident band and flange from the rest of the closure along the weakened line. A disadvantage of this closure is that the weakened line must be designed within a very fine tolerance, one that is not always satisfactorily achieved during manufacture. If the weakened line is not made sufficiently strong, the band and flange will sever from the rest of the closure during the initial installation of the closure on the filled container or during shipping and handling. When this occurs, the packaging process of the manufacturer is greatly disrupted, often resulting in the product located within the container being discarded. If the weakened line is strong enough so that it is not severed during the initial installation or during subsequent shipping and handling, the weakened line is often too strong to be readily opened by the ultimate consumer without the use of tools or other aids. Also, when the tamper evident portion is separated from the remainder of a closure along a weakened line, it is possible to remove the closure, tamper with the contents of the container and replace the closure. A consumer who does not subject the closure and container to close inspection, may not notice that the weakened line has been severed until after the purchase has been completed and an attempt is made to open the container for the first time. Further, as closures are often tightly turned onto the containers, a consumer may not even notice that the weakened line has been severed when they open the container for the first time.
PCT application Ser. No. US 91/05434 published on Mar. 5, 1992 describes a tamper indicating closure having a retaining hoop with relief windows extending from a hinged edge at least one-third of the distance toward a free edge. The windows are located to interrupt the hinged edge and create a series of spaced hinges around the circumference of the closure. The windows are located along the hinged edge so that the retainer can be moved from an outward molded position to an inward installation position much more easily so that the retainer does not have to be moved between the two positions by a separate step. With the present invention, the windows are spaced from the hinged edge. In Canadian Patent No. 1,182,782 issued on Feb. 19th, 1985, there is described a closure and container with screw threads made up of a series of projections in the shape of truncated cones so that the screw threads of the closure and container can interlock with one another. The projections were made by drilling successive holes into a core for use in a mold. The separate drilling of each hole can be extremely time consuming particularly when the spacing between holes and the depth of each hole must be identical.